Introduction: The highest damage to the sperm is caused by oxidative stress due to the production of reactive oxygen species (ROS). Semen cryopreservation causes some structural, biochemical and functional changes, which leads to various problems in sperm transport, survival and fertility rate in domestic animals. Also, sperm metabolism produces ROS, which is potentially harmful to the sperm plasma membrane integrity loss of motility. High concentrations of ROS have negative effects on sperm quality and increased degradation of DNA, lipid peroxidation and oxidative stress which inhibits sperm motility and changes in sperm infrastructure and finally the reduction of fertility. Seminal plasma contains enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) which have an important role in the inhibition of the deleterious effects of ROS. Lipid peroxidation may be due to lack of coordination between SOD, GPX, and CAT in seminal plasma or deficiency of total antioxidant capacity of the cell. Ellagic acid is a polyphenol compound that can be found in green tea and other natural resources such as pomegranate, strawberry, raspberry, walnut and eucalyptus bark. Ellagic acid showed antioxidant and anti-apoptotic effects, it can delay or prevent cellular oxidation; ultimately reduce oxidative stress. Ellagic acid increases the activity of enzymes SOD, CAT and GPx by preventing free radical attack to cells. This research was conducted to evaluate the antioxidant effect of different levels of Elligic acid on microscopic, biochemical parameters, antioxidant enzyme activities and total antioxidant capacity of ram semen after freezing-thawing process. Materials and Methods: Five Ghezel rams were used. Semen samples were collected twice a week using artificial vagina. In order to remove individual effects, the semen samples were pooled together. Different levels of ellagic acid (0. 25, 0. 5, 1, 1. 5 mM) were added in diluent of tris-lecithin based. After processing and freezing, the samples were stored in liquid nitrogen until the time of evaluation. After thawing of semen samples, sperm motility parameters were evaluated using CASA system, viability by with Eosin-nigrosin staining, membrane integrity with a solution of hypo-osmotic, sperm abnormalities using a solution of Hancock, lipid peroxidation by measuring malondialdehyde and the seminal plasma antioxidant enzymes of glutathione peroxidase, superoxide dismutase and total antioxidant capacity using the RANDOX Laboratories kit. The data were analyzed with SAS (9. 1. 3) software using GLM procedures. Results and Discussion: The results showed that the levels of 0. 25, 0. 5, 1 and 1. 5 mM ellagic acid improved survival and total motility parameters (P< 0. 05). Addition of 0. 5 mM ellagic acid reduced abnormal sperm, but improved the linearity motion, straight line velocity and average path velocity of sperm (P< 0. 05). Addition of 0. 25 mM level improved the curvilinear velocity compared to the control group. Total antioxidant capacity was improved in all the treated compared to the control group (P< 0. 05). Increasing TAC level in seminal plasma may have a significant role in sperm normality. No significant difference was found in the glutathione peroxidase activity and superoxide dismutase enzymes and malondialdehyde levels in treatments containing ellagic acid compared to the control group. Sperm have multiple mechanisms of defense against reactive oxygen species. These mechanisms include catalase, uric acid, taurine, thiols, ascorbic acid and α-tocopherol, but the superoxide dismutase, glutathione peroxidase and glutathione reductases are the most important ones. Apart from the increase in the activity of superoxide dismutase and glutathione peroxidase enzymes, ellagic acid probably had an impact on other factors to increase the total antioxidant capacity. All levels of ellagic acid nonsignificantly increased the plasma membrane integrity compared to the control group. The loss of sperm plasma membrane activity due to the lipid peroxidation may lead to loss of membrane fluidity and cell activity (Aitken and Sawyer, 2003). For this reason, addition of cryoprotectants and antioxidants to the extender can reduce the effects of cold shock on sperm. Conclusion: The findings of this study showed that the diluent containing 0. 5 mM ellagic acid significantly improved sperm parameters compared to other levels, after freezing-thawing process.